>> Cách a bfuil acat i tig
>> etir ith is blicht is mil,
>> nocha berair lat ar sét
>> in tan racha d'éc, a fhir.
>> The verb looks like the modern 2nd sg. present tense (or
>> subjunctive) "beirir", or possibly the future "béarfair".
> Isn't it just the 3rd sg. passive indicative present? Cf DIL B 56.55.
Oh gosh, yes. I thought of it, but was so fixated on the modern
forms in -t(h)- (EMI "beirthear"), and the OI future "bérthair
that I forgot OI present tense "berair, ·berar". According to
Liam Breatnach, by late MI the distinction between slender -ir
in the independent and the broad -ar in the dependent and relative
forms was beginning to break down ("Is cinnte, áfach, go raibh an
deighilt stairiúil idir foirceann neamhnasctha le -r caol agus
foirceann cónasctha agus coibneasta le -r leathan ag tosú ar
bhriseadh síos sa MG dhéanach..." SnaG lch. 297) He specifically
quotes our form: "in cáin truimm berair = an cháin throm a bheirtear".
So that seems to place "nocha berair" as late Middle Irish, since
it's not classical EMI.